PROJECT SUMMARY The goal of this fellowship is to prepare the applicant, Dr. Lauren A. Magee, for an independent academic research career focused on improving the health of adolescents and young adults (AYA) involved in firearm violence, with a long-term goal of interrupting the cycle of violence. The proposed fellowship consists of two complementary components: 1) a research project linking police and clinical care systems data to identify the overlaps and non-overlaps of firearm assault victimization events, as well as to analyze health care utilization and clinical diagnoses preceding these events; and 2) a training plan comprised of formal coursework in learning health systems and survival analysis, theoretical and content knowledge of clinical care utilization and health behaviors, clinical immersion experiences in emergency departments, mentored research, as well as other professional development activities. The specific aims of the research study are to conduct a retrospective cohort study of individuals age 10-27 between 2007 and 2016 in order to: 1) to examine the overlap and non-overlap of firearm assault event data within the police and clinical care data systems; and 2) to analyze healthcare utilization patterns prior to firearm assault events. This is a critical first step toward building a more comprehensive and integrated database of firearm assault events from both police and clinical systems and thereby identifying opportunities for primary prevention among firearm assault victims. The majority of existing research focuses solely on one data source, and each system has weaknesses in identifying and characterizing firearm assault events. In clinical data, firearm assault events are not always categorized with ICD code(s) indicating a firearm assault, and the justice data are missing the clinical utilization and diagnoses. This study will provide findings responding to: 1) the National Academy of Medicine?s priorities for research to improve data collection surrounding nonfatal firearm injuries, and 2) NICHD?s priority areas of firearm injury prevention, violence related injury, and emergency care. This study has the potential to assess the lasting impacts of nonfatal firearm injuries on AYA long-term health. This study is supported by a strong interdisciplinary mentorship team with expertise in clinical care systems, health services research, adolescent behavior, longitudinal data analysis, and firearm violence prevention. Both the research and training plans will prepare Dr. Magee to achieve her career objectives of improving the health of AYA involved in firearm violence, by identifying opportunities to implement primary prevention, and thus, interrupting the cycle of violence.